A canned type rotating electrical machine is used when an atmosphere between a rotor and a stator needs to be divided. In the canned type rotating electrical machine, the atmosphere in which the stator and the rotor are housed can be divided by a tubular member, called a can.
In consideration of the permeability of magnetic flux, a non-magnetic material needs to be used as the material of the can used in the canned type rotating electrical machine (in the case of metal, SUS316, for example). However, in the case of using the can made of metal, heat is generated on the can by eddy currents generated in accordance with magnetic field rotation of the stator, and this causes energy loss (can loss). Especially when the rotating speed is high, influences by this energy loss are significant and unignorable. Therefore, as the material of the can, it is desirable to use fiber reinforced plastic that is a non-magnetic electrical-insulating material.
PTL 1 explains that it has been discussed that the can is made of synthetic resin that excels in an electrical insulating property and corrosion resistance (paragraph 0006). In addition, PTL1 further explains that “Using the resin is advantageous in that the resin does not rust, and the resin is less likely to expand with heat than the metal. However, the resin cannot be fixed by welding to an inner periphery of the stator iron core and the reinforcing tube. Therefore, there is no choice but to use a seal structure using O rings at both end portions of the can. In the case of using the seal structure using the O rings, synthetic resin has problems regarding circularity and the like. In addition, the carbon-based synthetic resin is still in the process of development, so that it is considerably difficult to produce a thin can having a large bore and high circularity. Therefore, at present, there is no choice but to depend on the can made of metal” (paragraph 0007).